Cognition following computer-assisted total knee arthroplasty: a prospective cohort study

Abstract

Background: A substantial number of patients experience postoperative cognitive changes following total joint arthroplasty. The change in mental status may be the result of fat and bone-marrow-debris embolization. We hypothesized that the use of computer-assisted total knee arthroplasty, which does not involve the use of intramedullary alignment rods, would produce less fat and bone-marrow-debris embolization and, hence, fewer changes in mental status.

Methods: Forty-seven patients who underwent total knee arthroplasty with use of a computer-assisted navigation system and forty-eight patients who underwent conventional total knee arthroplasty without the assistance of computer navigation were followed prospectively. The validated Folstein Mini-Mental State Examination (MMSE) was used to assess the mental status of the patients. The test was administered preoperatively, serially postoperatively while the patient was in the hospital, and at six months. Medication and oxygen requirements were recorded.

Results: On the basis of the numbers studied, no significant differences in postoperative pain-medication or oxygen requirements were found between the group treated with computer-assisted navigation (the navigation group) and the group treated with conventional total knee arthroplasty (the control group). The mean postoperative MMSE score was 88.9 points in the navigation group and 89.3 points in the control group (p = 0.844). Twenty-five patients in the navigation group and thirty-six patients in the control group completed the test at six months. The mean score at that time was 95.3 points in the navigation group and 96.3 points in the control group (p = 0.514).

Conclusions: Further research is needed to determine if fat and bone-marrow-debris embolization is truly decreased by the use of computer-assisted total knee arthroplasty and if such a reduction has any clinical relevance.